Right before he dropped DAMN., Kendrick Lamar released a non-album track called “The Heart Part 4,” the fourth in a long-running series of loosies. And now, five days before the release of his apparent double-LP Mr. Morale & The Big Steppers, Kendrick is back with “The Heart Part 5.” It’s a decidedly sparse and funky track, one that puts a bright spotlight on K.Dot’s verse.